羊奶果的共生固氮及氮素的运转形式

Nitrogen fixation and transport form of organic N compounds in Elaeagnus conferta

对羊奶果根瘤的固氮、吸氢、防氧保护及固氮产物的运转进行研究。羊奶果是热带植物 ,离体根瘤固氮活性在 2 5～ 30℃时最高 ,且在离体 3h以内无显著变化 ;35～ 4 0℃的高温对根瘤吸氢活性有促进作用 ,离体根瘤的吸氢活性可保持 6 h以上 ;低温对固氮活性有明显的抑制作用。羊奶果为酰脲型植物 ,根、根瘤和木质部中都含有大量的尿囊酸 ,酰脲含量均占氮化合物总量的 5 0 %以上 ,说明它的根瘤和根都能将氮素转化成酰脲并经过木质部向上转运 ,还有部分氮素通过以丝氨酸、蛋氨酸为主的氨基酸形式运输。根瘤中未检测到血红蛋白 ,但有较高含量的 SOD、 ASA和

Elaeagnus conferta is a tropical actinorhizal plant,C 2H 2\|reduction and H 2\|uptake by excised root nodules was measured to determine the nitrogenase and hydrogenase activities at various temperatures,nodules showed maximum nitrogenase activity at 25-30℃ and no significant change was found within 3 hours.High temperature (35-40℃) enhanced the H 2 uptake by excised nodules,the hydrogenase activity kept in high level for at least 6 hours. E.conferta belong to ureide\|producing plant,a large quantity of allantoic acid was found in the extracts of nodules,roots and xylem of E.conferta grown without combined nitrogen.It was suggested that uride could be synthesized in the nodules and transported to the shoot of the plant.A little amino acids were found in the transported organic N compounds,such as Met,Ser.Hemoglobin was not found in nodules,instead, SOD activity and concentrations of ASA and GSH were high.